A NEW ASTRONOMY 209 



On the other hand, Tycho was not strong on the theoretical side. 

 He was never willing to accept the Copernican hypothesis of 

 rotation and orbital motion of the earth - - maintaining, for ex- 

 ample, that if the earth moved, a stone dropped from the top of a 

 tower must fall at a distance from the foot. Again with refer- 

 ence to the apparent displacement of the stars which would be 

 expected to result from orbital motion of the earth, he says : 



A yearly motion would relegate the sphere of the fixed stars to 

 such a distance that the path described by the earth must be insig- 

 nificant in comparison. Dost thou hold it possible that the space 

 between the sun, the alleged centre of the universe, and Saturn 

 amounts to not even -^ of that distance ? At the same time this 

 space must be void of stars. 



Sensible, however, of the weakness of the Ptolemaic theory, he 

 devised an ingenious compromise in which the planets revolved 

 about the Sun in their respective periods, and the entire heavens 

 about the earth daily all of which is not mathematically dif- 

 ferent from the Copernican theory. 



We see in him at the same time a perfect son of the sixteenth 

 century, believing the universe to be woven together by mysterious 

 connecting threads which the contemplation of the stars or of the 

 elements of nature might unravel, and thereby lift the veil of the 

 future; we see that he is still, like most of his contemporaries, a 

 believer in the solid spheres and the atmospherical origin of comets, 

 to which errors of the Aristotelean physics he was destined a few 

 years later to give the death-blow by his researches on comets ; 

 we see him also thoroughly discontented with his surroundings, and 

 looking abroad in the hope of finding somewhere else the place and 

 the means for carrying out his plans. 



As a practical astronomer Tycho has not been surpassed by any 

 observer of ancient or modern times. The splendor and number of 

 his instruments, the ingenuity which he exhibited in inventing new ones 

 and in improving and adding to those which were formerly known, 

 and his skill and assiduity as an observer, have given a character to 

 his labors and a value to his observations which will be appreciated 

 to the latest posterity. Brewster. 

 f 



